Research on Joint Operation of Reservoir Systems Considering Ecological Water Demand

To improve the utilization efficiency of water resources in river basins, this study takes the cascade hydropower reservoirs in the Long River Basin of the Three Gorges Reservoir Area as a case study. First, a hydrological model was constructed, achieving a Nash-Sutcliffe efficiency (NSE) of 0.76, a coefficient of determination ($\mathbf{R}^{\mathbf{2}}$) of $\mathbf{0. 8 7}$, and a relative error (RE) of $\mathbf{0. 8 0 \%}$, which accurately simulated the incoming runoff process. Subsequently, the ecological water demand process was determined based on the Tennant method and hydrodynamic modeling. Finally, a multi-objective joint operation model for the reservoir system was developed, integrating water supply, ecological requirements, and power generation objectives, with the goals of maximizing total hydropower generation and minimizing water shortages. The model was solved using the progressive optimality algorithm (POA), and the optimal operation scheme was selected via the TOPSIS method. The results indicate a clear trade-off among the three objectives (water supply, ecological conservation, and power generation). Under the balanced operation scheme (normal hydrological year), the ecological flow requirement was met $\mathbf{9 1. 1 \%}$ of the time, while the domestic water supply reliability reached $96.6 \%$, demonstrating significant comprehensive benefits. This study provides a scientific basis for the joint operation of cascade reservoirs in the Long River Basin.